Very low pH on a Porter - fixing?

[mr_wibble]

G'day,

I brewed a robust porter yesterday - lots of dark malts.
I also used tank water to do it (which has a naturally low pH)
I added 1 teaspoon of CaCO3 to the ~40 litres of liquor - mash & sparge.

I measured the pH about half-way through the mash.
I did this by putting about a teaspoon full into a (white) plate, and then putting a (small-range) litmus paper in it.

The room temperature pH was ~ 4.7 which gives the 68° mash a pH of 4.4 (pH is ~ 0.3 lower at mash temps Vs room temps1)
Ideally the pH should have been 5.2 - 5.62

I have made this beer many times before, but never measured the pH.
I know it will turn out well - it's SMWBO's favourite.
But I would like to brew a batch with a more optimal mash pH and see how it's different...

So Palmer says I should have added HCO3 to raise the pH of the mash.

But I don't understand how to calculate how much bicarb to add.

Theoretically my tank water has close-to-zero Ca, Mg and CaCO3. (this is a guess)

So filling out Palmer's water alkalinity nomograph gives me a line from 0 in "Mg (ppm)" through 0 in "Effective Hardness" finishing at 0 in "Ca (ppm)".
Now I draw a line going diagonally up from zero "Effective Hardness" to 20 on the "SRM" beer colour.

This passes through ~ 150ppm of HCO3. So that means I need to add /N/ teaspoons of bicarb until my ppm is 150?

Does this sound right?
How do I calculate /N/ ?
I tried his spreadsheet, but I don't know what I want my target water to be.

Could I just keep adding bicarb to the mash until I obtain a correct pH?
(and I guess, then use this amount at the start next time?)


Anyone have some sage advice?


cheers,
-kt


1 Gordon Strong "Brewing Better Beer"
2 Palmer "How to Brew" http://www.howtobrew.com/section3/chapter15-3.html

 

[manticle]

Chalk isn't very effective at raising pH unless it has been dissolved. My preferred way of dealing with this issue is simply to cold steep the roast malts for a few hours or overnight, raise temp to around 70 (I cold steep in a covered stainless pot) then add to the mash ten minutes before the end of the mash.

Alternatives and explanations may be found here: http://www.braukaiser.com/wiki/index.php?title=Building_brewing_water_with_dissolved_chalk

http://braukaiser.com/wiki/index.php?title=Mash_pH_control#Precipitation_of_calcium_carbonate

http://braukaiser.com/wiki/index.php?title=Alkalinity_reduction_with_slaked_lime

 

[mr_wibble]

Do you cold steep at the usual water:grist ratio ?

 

[seamad]

I steep my dark grains for 24hr in cold water and add the liquid to the kettle. Is there any reasoning for adding to the mash for 10 minutes manticle ?
cheers
sean

 

[seamad]

I use 4L/kg

 

[manticle]

Steep just to cover.
Add to the mash so I still get the benefit of hot steeped roasty goodness with no need to adjust pH up.

 

[mr_wibble]

thanks guys, I'll give it a go next brew.

 

[Ducatiboy stu]

Tank water has a ph of 7 which is right in the middle. If your tank water is lower than 7 then you have some contamination issues.

 

[lael]

How do the pros deal with dark beers? I can't see them doing cold steeping, or aging for a year to allow them to mellow. ( though I think porters used to be aged back in the day for a year or so and blended).

 

[billygoat]

Tank water has a ph of 7 which is right in the middle. If your tank water is lower than 7 then you have some contamination issues.

Have a read of this. Especially the 4th paragraph.
http://www.csiro.au/promos/ozadvances/Series14Acidrain.htm

 

[mr_wibble]

Tank water has a ph of 7 which is right in the middle. If your tank water is lower than 7 then you have some contamination issues.

Uh, that's not entirely accurate.

Falling through the air, rain water reacts with CO2 in the atmosphere forming carbonic acid.
This gives the rain water a lower pH usually around 5.71

cheers,
-kt

1 Wikipedia "Acid Rain" http://en.wikipedia.org/wiki/Acid_rain


EDIT: Just needed one more comma

 

[Dunkelbrau]

Like distilled water, once it sits to equalise the co2 into solution, it becomes slightly acidic.

If you are starting with ph 5 in your water, and adding roast malts you will lower it too far. I'd try diluting a portion of your water with tap/store water for dark beers if the ph is fine for lighter beers.

 

[mje1980]

How do the pros deal with dark beers? I can't see them doing cold steeping, or aging for a year to allow them to mellow. ( though I think porters used to be aged back in the day for a year or so and blended).

They'd simply adjust mash ph I imagine but don't know for sure. As you say they wouldn't be cold steeping etc.

For the last 5? Years I've just been adding dark malts in the last 10 mins of the mash. Just easy and I find I get a smoother roast flavour, no harshness.

 

[Parks]

The PH of your rain water is likely totally irrelevant as it has no PH buffering ability. It will go to whatever PH your grain bill and salt additions dictate.

My suggestion is to simply leave the roast grains out until the last 10min of the mash and you'll be sweet.

 

[ricardo]

How do the pros deal with dark beers? I can't see them doing cold steeping, or aging for a year to allow them to mellow. ( though I think porters used to be aged back in the day for a year or so and blended).

I'm no pro but use food grade pickling lime to raise the pH when brewing stouts and porters

 

[Parks]

How do the pros deal with dark beers? I can't see them doing cold steeping, or aging for a year to allow them to mellow. ( though I think porters used to be aged back in the day for a year or so and blended).

Porters were actually brown too before roasted malts were available.

 

[lael]

I'm no pro but use food grade pickling lime to raise the pH when brewing stouts and porters

Interesting. What are the rules for amounts and any special way to dissolve it needed?

 

[Ducatiboy stu]

Well mine was closer to 7 than 5.7

 

[Howlingdog]

Well mine was closer to 7 than 5.7

Yeah, buy you live in god's own country. What else would expect?

 

[Ducatiboy stu]

Yeah, buy you live in god's own country. What else would expect?

I would expect nothing less.